LONDON – The International Marine Contractors Association (IMCA) has issued a revised version of its ‘Guidance on Subsea Metrology’ (IMCA S 019 Rev. 1).
Subsea metrology determines the relative horizontal and vertical distance between subsea assets and their relative heading and attitude, and is mainly applied to pipeline connections.
Pipeline engineers use the resultant information to design a connecting piece to join the assets together.
These are often the final sections of the pipeline to be fitted and also one represent one of the last steps before first hydrocarbon production. For this reason, subsea metrology surveys must be timely and accurate.
If the connecting pieces are not to the required specification and/or do not fit correctly, their life span can be significantly reduced, or the process can add days to a construction vessel’s hire while the crew are waiting for repairs to the spool.
“IMCA’s revised document provides guidance on commonly used subsea metrology techniques deployed today,” said the association’s technical director Richard Benzie.
“These are long baseline (LBL) acoustics, both diver taut wire and digital taut wire, photogrammetry, inertial navigation systems (INS), SLAM techniques and laser scanning. “IMCA S 019 covers the basics of subsea metrology, engineering requirements, the different methods and technologies, and some of the advantages and limitations of each technique…
“However…the pace of technical change and ongoing development of deepwater fields means that other subsea metrology methods are being developed, including photogrammetric metrology, INS metrology, SLAM techniques and laser scanning, all of which are covered in the new document.”
IMCA S 019 is available online free of charge to members and for £75 ($99) to non-members. Details firstname.lastname@example.org.